I have a candidate table say candidates having only id field and i left joined profiles table to it. Table profiles has 2 fields namely, candidate_id & name.
e.g. Table candidates:
id
----
1
2
and Table profiles:
candidate_id name
----------------------------
1 Foobar
1 Foobar2
2 Foobar3
i want the latest name of a candidate in a single query which is given below:
SELECT C.id, P.name
FROM candidates C
LEFT JOIN profiles P ON P.candidate_id = C.id
GROUP BY C.id
ORDER BY P.name;
But this query returns:
1 Foobar
2 Foobar3
...Instead of:
1 Foobar2
2 Foobar3
The problem is that your PROFILES table doesn't provide a reliable means of figuring out what the latest name value is. There are two options for the PROFILES table:
Add a datetime column IE: created_date
Define an auto_increment column
The first option is the best - it's explicit, meaning the use of the column is absolutely obvious, and handles backdated entries better.
ALTER TABLE PROFILES ADD COLUMN created_date DATETIME
If you want the value to default to the current date & time when inserting a record if no value is provided, tack the following on to the end:
DEFAULT CURRENT_TIMESTAMP
With that in place, you'd use the following to get your desired result:
SELECT c.id,
p.name
FROM CANDIDATES c
LEFT JOIN PROFILES p ON p.candidate_id = c.id
JOIN (SELECT x.candidate_id,
MAX(x.created_date) AS max_date
FROM PROFILES x
GROUP BY x.candidate_id) y ON y.candidate_id = p.candidate_id
AND y.max_date = p.created_date
GROUP BY c.id
ORDER BY p.name
Use a subquery:
SELECT C.id, (SELECT P.name FROM profiles P WHERE P.candidate_id = C.id ORDER BY P.name LIMIT 1);
Related
I have a standard many-to-many schema like this:
items table:
id
name
1
foo
groups table:
id
name
slug
1
baz
qux
items_to_groups:
item_id
group_id
1
1
The groups.slug is used to query Group information. The ID is internal.
I need to query for items that are not in a specified group, but also need to include the group attributes (like name) in the result set.
The query is trivial without the need for values from the groups table, but I cannot figure out how to include them.
Here is my best attempt:
SELECT
g.slug,
g.name,
i.name
FROM
items AS i
LEFT JOIN items_to_groups AS itg ON i.id = itg.item_id
LEFT JOIN groups AS g ON itg.group_id = g.id
AND g.slug = 'group-slug-1'
WHERE
itg.item_id IS NULL;
Results:
||Item name 1
||Item name 2
Desired results:
group-slug-1|1|Item name 1
group-slug-1|1|Item name 2
Hmmm . . . I'm thinking:
select i.*, g.*
from items i cross join
groups g
where g.slug = 'group-slug-1' and
not exists (select 1
from items_to_groups ig
where ig.item_id = i.id and ig.group_id = g.id
);
I have 3 tables I need to put together.
The first table is my main transaction table where I need to get distinct transaction id numbers and company id. It has all the important keys. The transaction ids are not unique.
The second table has item info which is linked to transaction id numbers which are not unique and I need to pull items.
The third table has company info which has company id.
Now I've sold some of these with the first one through a group by id. The second through a subquery which creates unique ids and joins onto the first one.
The issue I'm having is the third one by company. I cannot seem to create a query that works in the above combinations. Any ideas?
As suggested here is my code. It works but that's because for the company I used count which doesn't give the correct number. How else can I get the company number to come out correct?
SELECT
dep.ItemIDAPK,
dep.TotalOne,
dep.company,
company.vendname,
appd.ItemIDAPK,
appd.ItemName
FROM (
SELECT
csi.ItemIDAPK,
sum(f.TotalOne) as TotalOne,
count(f.DimCurrentcompanyID) company
FROM dbo.ReportOne F with (nolock)
INNER JOIN dbo.DSaleItem csi with (nolock)
on f.DSaleItemID = csi.DSaleItemID
INNER JOIN dbo.DimCurrentcompany cv
ON f.DimCurrentcompanyID = cv.DimCurrentcompanyID
INNER JOIN dbo.DimDate dat
on f.DimDateID = dat.DimDateID
where (
dat.date >='2013-01-29 00:00:00.000'
and dat.date <= '2013-01-30 00:00:00.000'
)
GROUP BY csi.ItemIDAPK
) as dep
INNER JOIN (
SELECT
vend.DimCurrentcompanyID,
vend.Name vendname
FROM dbo.DimCurrentcompany vend
) As company
on dep.company = company.DimCurrentcompanyID
INNER JOIN (
SELECT
c2.ItemIDAPK,
ItemName
FROM (
SELECT DISTINCT ItemIDAPK
FROM dbo.dimitem AS C
) AS c1
JOIN dbo.dimitem AS c2 ON c1.ItemIDAPK = c2.ItemIDAPK
) as appd
ON dep.ItemIDAPK = appd.ItemIDAPK
For further information my output is the following example, I know the code executes and the companyid is incorrect as I just put it with a (count) in their to make the above code execute:
Current Results:
Item Number TLS CompanyID Company Name Item Number Item Name
111111 300 303 Johnson Corp 29323 Soap
Proposed Results:
Item Number TLS CompanyID Company Name Item Number Item Name
111111 300 29 Johnson Corp 29323 Soap
I have 3 tables:
Person (with a column PersonKey)
Telephone (with columns Tel_NumberKey, Tel_Number, Tel_NumberType e.g. 1=home, 2=mobile)
xref_Person+Telephone (columns PersonKey, Tel_NumberKey, CreatedDate, ModifiedDate)
I'm looking to get the most recent (e.g. the highest Tel_NumberKey) from the xref_Person+Telephone for each Person and use that Tel_NumberKey to get the actual Tel_Number from the Telephone table.
The problem I am having is that I keep getting duplicates for the same Tel_NumberKey. I also need to be sure I get both the home and mobile from the Telephone table, which I've been looking to do via 2 individual joins for each Tel_NumberType - again getting duplicates.
Been trying the following but to no avail:
-- For HOME
SELECT
p.PersonKey, pn.Phone_Number, pn.Tel_NumberKey
FROM
Persons AS p
INNER JOIN
xref_Person+Telephone AS x ON p.PersonKey = x.PersonKey
INNER JOIN
Telephone AS pn ON x.Tel_NumberKey = pn.Tel_NumberKey
WHERE
pn.Tel_NumberType = 1 -- e.g. Home phone number
AND pn.Tel_NumberKey = (SELECT MAX(pn1.Tel_NumberKey) AS Tel_NumberKey
FROM Person AS p1
INNER JOIN xref_Person+Telephone AS x1 ON p1.PersonKey = x1.PersonKey
INNER JOIN Telephone AS pn1 ON x1.Tel_NumberKey = pn1.Tel_NumberKey
WHERE pn1.Tel_NumberType = 1
AND p1.PersonKey = p.PersonKey
AND pn1.Tel_Number = pn.Tel_Number)
ORDER BY
p.PersonKey
And have been looking over the following links but again keep getting duplicates.
SQL select max(date) and corresponding value
How can I SELECT rows with MAX(Column value), DISTINCT by another column in SQL?
SQL Server: SELECT only the rows with MAX(DATE)
Am sure this must be possible but been at this a couple of days and can't believe its that difficult to get the most recent / highest value when referencing 3 tables. Any help greatly appreciated.
select *
from
( SELECT p.PersonKey, pn.Phone_Number, pn.Tel_NumberKey
, row_number() over (partition by p.PersonKey, pn.Phone_Number order by pn.Tel_NumberKey desc) rn
FROM
Persons AS p
INNER JOIN
xref_Person+Telephone AS x ON p.PersonKey = x.PersonKey
INNER JOIN
Telephone AS pn ON x.Tel_NumberKey = pn.Tel_NumberKey
WHERE
pn.Tel_NumberType = 1
) tt
where tt.rn = 1
ORDER BY
tt.PersonKey
you have to use max() function and then you have to order by rownum in descending order like.
select f.empno
from(select max(empno) empno from emp e
group by rownum)f
order by rownum desc
It will give you all employees having highest employee number to lowest employee number. Now implement it with your case then let me know.
Please don't downgrade this as it is bit complex for me to explain. I'm working on data migration so some of the structures look weird because it was designed by someone like that.
For ex, I have a table Person with PersonID and PersonName as columns. I have duplicates in the table.
I have Details table where I have PersonName stored in a column. This PersonName may or may not exist in the Person table. I need to retrieve PersonID from the matching records otherwise put some hardcode value in PersonID.
I can't write below query because PersonName is duplicated in Person Table, this join doubles the rows if there is a matching record due to join.
SELECT d.Fields, PersonID
FROM Details d
JOIN Person p ON d.PersonName = p.PersonName
The below query works but I don't know how to replace "NULL" with some value I want in place of NULL
SELECT d.Fields, (SELECT TOP 1 PersonID FROM Person where PersonName = d.PersonName )
FROM Details d
So, there are some PersonNames in the Details table which are not existent in Person table. How do I write CASE WHEN in this case?
I tried below but it didn't work
SELECT d.Fields,
CASE WHEN (SELECT TOP 1 PersonID
FROM Person
WHERE PersonName = d.PersonName) = null
THEN 123
ELSE (SELECT TOP 1 PersonID
FROM Person
WHERE PersonName = d.PersonName) END Name
FROM Details d
This query is still showing the same output as 2nd query. Please advise me on this. Let me know, if I'm unclear anywhere. Thanks
well.. I figured I can put ISNULL on top of SELECT to make it work.
SELECT d.Fields,
ISNULL(SELECT TOP 1 p.PersonID
FROM Person p where p.PersonName = d.PersonName, 124) id
FROM Details d
A simple left outer join to pull back all persons with an optional match on the details table should work with a case statement to get your desired result.
SELECT
*
FROM
(
SELECT
Instance=ROW_NUMBER() OVER (PARTITION BY PersonName),
PersonID=CASE WHEN d.PersonName IS NULL THEN 'XXXX' ELSE p.PersonID END,
d.Fields
FROM
Person p
LEFT OUTER JOIN Details d on d.PersonName=p.PersonName
)AS X
WHERE
Instance=1
Ooh goody, a chance to use two LEFT JOINs. The first will list the IDs where they exist, and insert a default otherwise; the second will eliminate the duplicates.
SELECT d.Fields, ISNULL(p1.PersonID, 123)
FROM Details d
LEFT JOIN Person p1 ON d.PersonName = p1.PersonName
LEFT JOIN Person p2 ON p2.PersonName = p1.PersonName
AND p2.PersonID < p1.PersonID
WHERE p2.PersonID IS NULL
You could use common table expressions to build up the missing datasets, i.e. your complete Person table, then join that to your Detail table as follows;
declare #n int;
-- set your default PersonID here;
set #n = 123;
-- Make sure previous SQL statement is terminated with semilcolon for with clause to parse successfully.
-- First build our unique list of names from table Detail.
with cteUniqueDetailPerson
(
[PersonName]
)
as
(
select distinct [PersonName]
from [Details]
)
-- Second get unique Person entries and record the most recent PersonID value as the active Person.
, cteUniquePersonPerson
(
[PersonID]
, [PersonName]
)
as
(
select
max([PersonID]) -- if you wanted the original Person record instead of the last, change this to min.
, [PersonName]
from [Person]
group by [PersonName]
)
-- Third join unique datasets to get the PersonID when there is a match, otherwise use our default id #n.
-- NB, this would also include records when a Person exists with no Detail rows (they are filtered out with the final inner join)
, cteSudoPerson
(
[PersonID]
, [PersonName]
)
as
(
select
coalesce(upp.[PersonID],#n) as [PersonID]
coalesce(upp.[PersonName],udp.[PersonName]) as [PersonName]
from cteUniquePersonPerson upp
full outer join cteUniqueDetailPerson udp
on udp.[PersonName] = p.[PersonName]
)
-- Fourth, join detail to the sudo person table that includes either the original ID or our default ID.
select
d.[Fields]
, sp.[PersonID]
from [Details] d
inner join cteSudoPerson sp
on sp.[PersonName] = d.[PersonName];
Imagine you have two tables, with a one to many relationship.
For this example, I will suggest that there are two tables: Person, and Homes.
The person table holds a persons name, and gives them an ID. The homes table, holds the association of homes to a person. PID joins to "Person.ID"
And, in this tiny DB, a person can have no homes, or many homes.
I hope I drew that right.
How do I write a select, that returns everyone with every specified house type?
Let's say these are valid "Types" in the homes table:
Cottage, Main, Mansion, Spaceport.
I want to return everyone, in the Person table, who has a spaceport and a Cottage.
The best I could come up with was this:
SELECT DISTINCT( p.name ) AS name
FROM person p
INNER JOIN homes h ON h.pid = p.id
WHERE 'spaceport' in (
SELECT DISTINCT( type ) AS type
FROM homes
WHERE pid = p.id
)
AND 'cottage' in (
SELECT DISTINCT( type ) AS type
FROM homes
WHERE pid = p.id
)
When I wrote that, it works, but I'm pretty sure there has to be a better way.
The HAVING clause here will guarantee that the persons returned have both types, not just one or the other.
SELECT p.name
FROM person p
INNER JOIN homes h
ON p.id = h.pid
AND h.type IN ('spaceport', 'cottage')
GROUP BY p.name
HAVING COUNT(DISTINCT h.type) = 2
select * from homes;
home_id person_id type
--
1 1 cottage
2 1 mansion
3 2 cottage
4 3 mansion
5 4 cottage
6 4 cottage
To find the id numbers of every person who has both a cottage and a mansion, group by the id number, restrict the output to cottages and mansions, and count the distinct types.
select person_id
from homes
where type in ('cottage','mansion')
group by person_id
having count(distinct type) = 2;
person_id
--
1
You can use this query in a join to get all the columns from the person table.
select person.*
from person
inner join (select person_id
from homes
where type in ('cottage','mansion')
group by person_id
having count(distinct type) = 2) T
on person.person_id = T.person_id;
Thanks to Joe for pointing out an error in my count().
Not sure about the performance on this one, but here goes:
SELECT PID FROM (
SELECT PID, COUNT(PID) cnt FROM (
SELECT DISTINCT PID, Type FROM Homes
WHERE Type IN ('Type1', 'Type2', 'Type3')
) a
GROUP BY PID
) b
WHERE b.cnt = 3
You'd have to dynamically generate your IN clause as well as the WHERE b.CNT clause.